fix cold start time increase issue

[kinderyj]

Fixes #15477

Proposed Changes

• For Kubernetes clusters without mesh enabled, it's preferable to probe the pod directly. However, if podsAddressable is set to false, the activator will continuously probe the cluster, leading to significantly longer cold start times. To re-enable pod probing, you must restart the activator pod. This is because the podsAddressable setting resets to its default value of true only during the activator's startup and initialization.

Release Note

Fix cold start time increase issue.

[linux-foundation-easycla[bot]]

The committers listed above are authorized under a signed CLA.

• :white_check_mark: login: kinderyj / name: Matt Wang (bd3567511271775f80bd1a6bab8c05a6f32567c6)

[knative-prow[bot]]

Welcome @kinderyj! It looks like this is your first PR to knative/serving 🎉

[knative-prow[bot]]

Hi @kinderyj. Thanks for your PR.

I'm waiting for a knative member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: kinderyj Once this PR has been reviewed and has the lgtm label, please assign davidhadas for approval. For more information see the Kubernetes Code Review Process.

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[dprotaso]

/ok-to-test

[dprotaso]

@kinderyj do you have repro steps on triggering the podAddressable flag change?

There's also another instance where podAddressable is switched to false - https://github.com/knative/serving/blob/df030277a7be5bfa869e1b6e1f60e29502393a3a/pkg/autoscaler/metrics/stats_scraper.go#L238

So I don't know if your PR covers all cases here

[knative-prow[bot]]

@kinderyj: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
unit-tests_serving_main	bd3567511271775f80bd1a6bab8c05a6f32567c6	link	true	/test unit-tests

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[dprotaso]

Change breaks some unit tests

[dprotaso]

@kinderyj any interesting in following up on this PR?

[github-actions[bot]]

This Pull Request is stale because it has been open for 90 days with no activity. It will automatically close after 30 more days of inactivity. Reopen with /reopen. Mark as fresh by adding the comment /remove-lifecycle stale.

[github-actions[bot]]

This Pull Request is stale because it has been open for 90 days with no activity. It will automatically close after 30 more days of inactivity. Reopen with /reopen. Mark as fresh by adding the comment /remove-lifecycle stale.